Traditional hydropower plants require the installation of a dam which in turn requires a landscape suitable to massive engineering works and causes a huge environmental impact. On the other hand, wind turbines typically generate only about one fifth of the energy they are rated at due to the intermittent nature of wind power. Moreover, water has much more specific mass than air. The amount of kinetic energy that passes through a turbine is:
      K    e    =            1      2        ×    M    ×          V      2      
where M is the mass of the water flowing through the turbine and V is its velocity. A unit of volume of water weighs about 854 times as the same volume of air at sea level, so a water turbine can yield much more energy than a wind turbine of the same size. Unfortunately, the construction costs and environmental drawbacks associated with the building of a dam often render hydropower an unattractive proposition.